Luminaire device

#The present invention is concerned generally with a luminaire device for providing selected light illumination. More particularly, the invention is concerned with luminaires, such as a wedge, for backlighting by light output from a liquid crystal display layer and also by manipulating light polarization, recycling light of selected polarization and filtering selected light polarizations to enhance light illumination and image output.

#A variety of applications exist for luminaire devices, such as, for liquid crystal displays. For flat panel liquid crystal displays, it is important to provide adequate backlighting while maintaining a compact lighting source. It is known to use wedge shaped optical devices for general illumination purposes. Light is input to such devices at the larger end; and light is then internally reflected off the wedge surfaces until the critical angle of the reflecting interface is reached, after which light is output from the wedge device. Such devices, however, have only been used to generally deliver an uncollimated lighting output and often have undesirable spatial and angular output distributions. For example, some of these devices use white painted layers as diffuse reflectors to generate uncollimated output light.

#It is therefore an object of the invention to provide an improved optical device and method of manufacture.

#FIG. 1 shows a prior art wedge shaped device;

#FIG. 2A illustrates a multilayer tapered luminaire device constructed in accordance with the invention;

#FIG. 2B is a magnified partial view of the junction of the wedge layer, the first layer and the second faceted layer;

#A multilayer luminaire device constructed in accordance with one form of the invention is illustrated in FIG. 2 and indicated generally at 10. A prior art wedge 11 is shown generally in FIG. 1. In this wedge 11 the light rays within the wedge 11 reflect from the surfaces until the angle of incidence is less than the critical angle (sin.sup.-1 1/n) where n is the index of refraction of the wedge 11. The light can exit equally from both top and bottom surfaces of the wedge 11, as well as exiting at grazing angles.

#The multilayer luminaire device 10 (hereinafter "device 10") shown in FIG. 2A includes a base or wedge layer 12 which has a characteristic optical index of refraction of n.sub.1. The term "wedge layer" shall be used herein to include all geometries having converging top and bottom surfaces with wedge shaped cross sectional areas. The x, y and z axes are indicated within FIGS. 2A and 2C with the "y" axis perpendicular to the paper. Typical useful materials for the wedge layer 12 include almost any transparent material, such as glass, polymethyl methacrylate, polystyrene, polycarbonate, polyvinyl chloride, methyl methacrylate/styrene copolymer (NAS) and styrene/acrylonitrile. The wedge layer 12 in FIG. 2A further includes a top surface 14, a bottom surface 16, side surfaces 18, edge 26 and a back surface 20 of thickness to spanning the top, bottom and side surfaces. A light source, such as a tubular fluorescent light 22, injects light 24 through the back surface 20 into the wedge layer 12. The light 24 is internally reflected from the various wedge layer surfaces and is directed along the wedge layer 12 toward the edge 26. Other possible light sources can be used and will be described hereinafter. Generally, conventional light sources provide substantially incoherent, uncollimated light; but coherent, collimated light can also be processed by the inventions herein.

#For the case where the surfaces 14 and 16 are flat, a single angle of inclination .phi. for a linear wedge is defined by the top surface 14 and the bottom surface 16. In the case of nonlinear wedges, a continuum of angles .phi. are definable; and the nonlinear wedge can be designed to provide the desired control of light output or concentration. Such a nonlinear wedge will be described in more detail later.